Normal blood coagulation

Definition of Haemostasis : refers to the arrest of bleeding, by prevention blood loss the blood vessels,

mechanism of coagulation: - fibrinolysis :dissolving of clotting to maintain patency of circulation

**How Blood clotting occurs -tissues are damaged : platelets break down, thromboplastin is released. 2- prothrombin converted into thrombin by assistance of calcium ions, and thromboplastin

3-Thrombin is a proteolytic (protein-splitting) enzyme that converts fibrinogen into fibrin. -Fibrinolysis is the breakdown of fibrin and occurs as a response to the presence of clotted blood

- heparin, which is produced in the liver make dissolving of this fibrin blood clot * characteristics of Fibrin: - a network of long, sticky strands that entrap blood cells(coagulation material ) to establish a clot

-The coagulated material: clotting factors. 13 in number. -breaks down the fibrin in the clots, by plasmin will produces fibrin degradation products (FDPs).

Disseminated intravascular coagulation Definition : DIC is a situation of inappropriate coagulation within the blood vessels. Result : 1-consumption of clotting factors. 2-failure of clotting at the bleeding site.

*DIC is rare when the fetus is alive, and it usually starts to resolve when the baby is born Etiology: DIC is never a primary disease it always occurs as a response to another disease process. pathology : formation of micro thrombi throughout the circulation. Clotting factors are used up.

The DIC triggers fibrinolysis and the production of FDPs. A paradoxical feedback: clotting is the primary problem, but hemorrhage is the predominant clinical finding.

When DIC occurs during or after birth. 1 -reduce level of clotting factors. 2-the presence of FDPs,so action of FDPs;

1- prevent normal haemostasis at the placental site. 2- FDPs reduce the efficiency of normal clotting. 3- inhibit myometrial action 4-prevent the uterine muscle from constricting the blood vessels in the normal way.

Picture : -Torrential hemorrhage may be the outcome. -Visible blood loss may be observed. -blood remain uncoagulated for several minutes and even when clotting does occur, the clot is unstable

-*Micro thrombi may cause: - circulatory obstruction in the small blood vessels. - cyanosis of fingers and toes. - cerebrovascular accidents - failure of organs such as the liver and kidneys

Events that trigger DIC Placental abruption Intrauterine fetal death including delayed miscarriage Amniotic fluid embolism Intrauterine infection including septic abortion Pre-eclampsia and eclampsia

abruption -damage of tissue at the placental site,thromboplastin are released into the circulation and may cause DIC. -If the placenta is delivered as soon as possible after the abruption the risk of DIC is reduced. (Vaginal birth where possible is often favored over caesarean birth to reduce the risk of postpartum hemorrhage.)

fetal death -If a dead fetus is retained in utero for more than 3 or 4 weeks, -thromboplastins are released from the dead fetal tissues. - thromboplastein enter the maternal circulation and deplete clotting factors. - IOL should be done, with the woman's consent. -clotting studies should be performed prior to induction of labor

fluid embolism - DIC may develop, through release of Thromboplastin in the amniotic fluid is responsible for setting off the cascade of clotting.

infection The causes of this include; -Septic abortion. - Hydatidiform mole. -placenta accretes - Endometrial infection before or after birth. * DIC is caused by endo toxins entering the circulation and damaging the blood vessels. -The infection itself must be treated with antibiotics

-monitor for developing hemolytic septicemia, any blood administered may be destroyed by the bacteria in the bloodstream. -The baby needs treatment following birth if the infection was ante partum. --In postpartum infection, any retained products may need E&C

and eclampsia: -predispose woman to abruption placenta that could lead to DIC

Management: -The midwife should be alert for signs that clotting is abnormal - Assessment of the nature of the clot, during the third stage of labor. -Oozing from a venepuncture, bleeding from nose or mouth should be observed.. CBC and blood group. -clotting studies. -platelets count. - Fibrinogen and FDPs

Treatment: --replacement of blood cells and clotting factors. - Administration of fresh frozen plasma and platelet. - The use of fresh whole blood is not now common. -Management is carried out by a team of obstetricians, anesthetists, hematologists, midwives and other health professionals

Care by the midwife -. The midwife has to maintain her own calmness and clarity of thinking as well as helping the couple to deal with the situation. - Frequent and accurate observations must be maintained in order to monitor the woman's condition. -Blood pressure, respirations, pulse rate and temperature are recorded.

The general condition is noted. - Fluid balance is monitored for any sign of renal failure. - The midwife must give him appropriate attention. -kept informed of what is happening. -psychological support